The purpose of this prospective study is to examine the pathophysiology of neonatal seizures and their consequences in order to establish a comprehensive basis for the continued investigation and clinical management of seizures in the newborn. The relationship between maturational, metabolic, autonomic and etiologic factors in the determination of the clinical and electroencephalographic expression of neonatal seizures will be explored initially by testing three specific hypotheses: 1) Activation of the autonomic nervous system is a frequent, but not widely appreciated feature of neonatal seizures which may extend neurological injury; 2) Depression of cortical inhibitory influences on normal tonic brainstem facilitory mechanisms may initiate nonepileptic tonic activity which may appear epileptic by current criteria; 3) Acute disturbances of the metabolic state of the newborn may alter patterns of epileptic activity or may produce depression of forebrain activity and thereby initiate nonepileptic tonic activity. Preliminary to the testing of the hypotheses will be the precise characterization of the full range of behavioral, motor, autonomic and neurophysiological manifestations of neonatal seizures which will, in turn, serve as the substrate for their classification. The study will be accomplished through the application of a newly designed and fabricated cribside monitoring system that permits prolonged recording in the neonatal intensive care unit without interfering with the patient's medical care. The following physiological parameters will be recorded continuously with this time-synchronized monitoring system: electroencephalogram, electromyogram, electrooculogram, electrocardiogram, triaxial accelerometry, respiratory movements, expired pCO2, transcutaneous pO2, oropharyngeal airway flow, and systemic blood pressure. The proposal also identifies specific training objectives for the teacher-investigator to acquire new investigatory skills. These include the development of technical and interpretative skills, and the establishment of a more complete conceptual basis of the developmental neurobiology of the premature and full-term newborn.